<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0, maximum-scale=1, user-scalable=no">
    <style>
        body,html{
            margin: 0;
            padding: 0;
            width: 100%;
            height: 100%;
            font-size: 14px;
        }
        .HolyGrail {
            display: -webkit-flex;
            display: flex;
            min-height: 100px;
            flex-direction: column;
        }

        header,
        footer {
            text-align: center;
            /* flex: 1;设置为1则顶体尾平分body */
            height: 50px;
            background: #ccc;
        }

        .HolyGrail-body {
            display: -webkit-flex;
            display: flex;
            flex: 1;
        }

        .HolyGrail-content {
            flex: 1;
            background: pink;
        }

        .HolyGrail-nav, .HolyGrail-ads {
            /* 两个边栏的宽度不放大也不缩小设为固定2em */
            flex: 0 0 2em;
        }

        .HolyGrail-nav {
            /* 导航放到最左边 */
            order: -1;
        }
        /* @media (max-width: 768px) {
          .HolyGrail-body {
            flex-direction: column;
            flex: 1;
          }
          .HolyGrail-nav,
          .HolyGrail-ads,
          .HolyGrail-content {
            flex: auto;
          }
        } */
        .Site {
          display: -webkit-flex;
          display: flex;
          min-height: 100vh;/*1vh表示浏览器高度的1%，100vh为浏览器高度，感觉这个挺好的*/
          /* min-height: 100%;另一种写法 */
          flex-direction: column;
        }

        .Site-content {
          flex: 1;
          overflow-y: scroll;
          background: #0099ff;
        }
    </style>
</head>
<body class="Site">
    <header>爱淘宝</header>
    <div class="HolyGrail-body Site-content">
        <main class="HolyGrail-content" style="height: 1000px;">...</main>
        <nav class="HolyGrail-nav">...</nav>
        <aside class="HolyGrail-ads">...</aside>
    </div>
    <footer>淘宝底部</footer>
</body>
</html>